Sure he could, but things like that happen all the time. Countless people start forks and new projects every day, while they could improve the existing ones (the world is full of examples).

I have this darwinian vision of the software world where it's extremely positive to experiment with new stuff. Only time will tell which things surpass the test of time.

Attacking someone publicly this way just because he doesn't contribute to your¹ favorite project is, in my opinion, a sick thing to do.

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1: Not addressing you in particular.

jack? That's a completely different user-case.